SPEED_OF_LIGHT_CGS  = 2.99792E10
'''The speed of light in cm/s'''
ELECTRON_CHARGE_C   = -1.6022e-19
'''The charge of the electron in Coulombs'''
ELECTRON_MASS_GEV   = 5.10998910e-4
'''The mass of the electron in GeV'''
PROTON_MASS_GEV     = 0.938272029
'''The mass of the proton in GeV'''
NEUTRON_MASS_GEV    = 0.939565560
'''The mass of the neutron in GeV'''
PIZERO_MASS_GEV     = 0.1349766
'''The mass of the :math:`\pi^0` in GeV'''
PICHARGED_MASS_GEV  = 0.13957018
'''The mass of the :math:`\pi^+` and :math:`\pi^-` in GeV'''
KCHARGED_MASS_GEV   = 0.493677
'''The mass of the :math:`K^+` and :math:`K^-` in GeV'''

geant_pid_gev = {2: ELECTRON_MASS_GEV,
                 3: ELECTRON_MASS_GEV,
                 7: PIZERO_MASS_GEV,
                 8: PICHARGED_MASS_GEV,
                 9: PICHARGED_MASS_GEV,
                 11: KCHARGED_MASS_GEV,
                 12: KCHARGED_MASS_GEV,
                 13: NEUTRON_MASS_GEV,
                 14: PROTON_MASS_GEV,
                 15: PROTON_MASS_GEV,
                 }
'''A dictionary of the above masses keyed by their GEANT id number.'''
